Gabapentin, (1-aminomethyl)cyclohexane-1-acetic acid) is an antiepileptic drug, which has been found to have pain-relieving properties. Gabapentin is indicated for the management of post-herpetic neuralgia in adults. It is reported as adjunctive therapy in the treatment of partial seizures with and without secondary generalization in patients over 12 years of age with epilepsy and in the treatment of partial seizures in pediatric patients age 3-12 years. Additionally, it is indicated to have anti-anxiety activity as also beneficial properties in treating neuro-degenerative diseases like Alzheimer's.
There can be a variable relationship between the dose of gabapentin and the resulting serum drug concentration that provides a therapeutic effect. This can be due to variability of intra- and inter-individual pharmacokinetics. As a result of this variability, equal doses of the same drug in different individuals can result in dramatically different clinical outcomes. For example, effectiveness of the same gabapentin dosage can vary significantly between patients based upon individual drug clearance and the ultimate serum drug concentration in the patient. In addition, therapeutic drug management of gabapentin can serve as an excellent tool to ensure compliance in administering chemotherapy with the actual prescribed dosage and achievement of the effective serum concentration levels.
Therapeutic drug management (TDM) can provide the clinician with insight on patient variation, and allow the clinical to individualize drug dosages to the patient's needs. For example, absorption of gabapentin can be saturated as the dose is titrated, so physicians may use TDM to confirm the plasma concentration increases with increasing doses. Thus, monitoring of levels of gabapentin in the body, and adjusting the dose as may be advised, can serve to better control therapy and limit undesirable side effects in patients.
The majority of data regarding gabapentin drug levels has been derived using either liquid chromatographic (Hengy & Kolle, 1985; Ratnaraj & Patsalos 1998, Chollet et al, 200, Wad & Kramer, 1998, Ifa et al. 2001) or gas chromatographic techniques (Hooper et al., 1990, Kushnir et al., 1999). While chromatographic techniques can be used to determine drug levels, such methods are impractical for commercial use due to, for example, long sample preparation time, long assay time, high cost, and labor-intensive procedures. Immunoassays provide simple and fast analytical methods for measurement of drug levels.